Many buyers want to have a Chinese manufacturer work on their own designs. And, very often, it means mould(s) need to be created for each new product design.

But creating a mould is expensive. If the supplier doesn’t already know the buyer, he will probably ask the buyer to send a payment.

In the importer’s side, it means they need to send money to a new supplier (who hasn’t demonstrated his ability to produce at the right quality standard).

And then, to send money again before production starts (the famous “deposit” which is actually an advance payment).

It is understandable that the buyer wants to check whether the moulds were done right. But how to check the mould’s quality?

Here is what I usually write to clients who need an inspection on plastic injection moulds.

Regarding the material composition

You want to make sure the steel is hard enough. But how to make sure about this?

In the best case, the factory has XRF (chemical) testing as well as (physical) hardness capability, to confirm the grade of metal used.

If they don’t, the inspector can ask for certifications of materials. Sometimes they are fake, but that’s not as frequent for moulds or tools as it is for a production batch.

Unfortunately, sending a mold core to a testing lab is not very practical.

Regarding the dimensions

There are two cases:

1. You gave the drawing of the mould/tool to the supplier.

In this case, all we need to do is check the mould’s dimensions.

In an ideal world, the manufacturer should have CMM testing capabilities. If not, using calipers is possible but not very precise.

Another option is to ask the manufacturer to physically bring the whole mould to a testing laboratory that has CMM capability.

2. You only gave the drawing of the finished product (to be made with the mould) to the supplier.

We’ll need to know the material of the finished products, because we need to estimate its shrink rate (after it gets out of the mould). For example, nylon has a higher shrink rate than polycarbonate.

We can use software to estimate by how much each dimension will shrink, and it allows us to know the dimensions the mould should have. And then, we can use CMM or calipers to estimate whether dimensions are right (back to point 1).